The new su PATH behavior

The su command that's now being packaged with Debian sid has significant change in behavior. In the past, when you did an:

$ su

the PATH would get set to root's PATH. Now, it remains the user's path:

$ su
Password:
# echo $PATH
/home/mithat/bin:/usr/local/bin:/usr/bin:/bin:/usr/local/games:/usr/games:/snap/bin

This means you won't pick up /usr/sbin where a lot of commands you'd typically use with root privileges live.

The fix to this is that you now have to append a dash to the command:

$ su -
Password:
# echo $PATH
/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/snap/bin

I don't know whether this impacts gksu or if sudo and/or gksudo are affected. gksu is affected as well, but with gksu there doesn't appear to be a way to get back to the old behavior.